Driving device for a sound recording substrate

ABSTRACT

A motion-picture film transport apparatus including a stepwise operating pilot motor and a uniform speed slave motor, the speed of which is controlled by a slack loop forming movable element, wherein an external synchronizing source generates synchronizing pulses acting on the stepwise operating motor and on a clutch energizable for bringing the film into operative engagement with a capstan and flywheel arrangement driven by the slave motor. The slave motor remains permanently in operation even when the advancing of the film is temporarily interrupted, and the restarting of the film may thus take place without introducing sound pitch perturbations.

United States Patent [191 1111 3,801,192 Vaast 5] Apr. 2, 1974 1 DRIVING DEVICE FOR A SOUND RECORDING SUBSTRATE Primary Examiner-Samuel S. Matthews Assistant ExaminerMichael L. Gellner [75] Inventor. Charles Vaast, Bezons, France Attorney, Agent, or Firm YOung & Thompson [73] Assignee: Societe Beaulieu S.A.,

Fontenay-sous-Bois (Val de Marne), France [5 7] ABSTRACT ment driven by the slave motor. The slave motor remains permanently in operation even when the advancing of the film is temporarily interrupted, and the restarting of the film may thus take place without introducing sound pitch perturbations.

2 Claims, 1 Drawing Figure DRIVING DEVICE FOR A SOUND RECORDING SUBSTRATE BACKGROUND OF THE INVENTION DESCRIPTION OF A PREFERRED EMBODIMENT According to the embodiment shown herein, the re- The present invention relates to a driving device for 5 cording substrate or strip in the present case is a moa sound recording substrate or strip associated with a motion-picture film.

Regardless of whether the sound information corresponding to a motion picture film is stored on a separate magnetic tape or on a sound track which is part of the film substrate, it is difficult to assure the synchronization of the movement of the sound recording substrate with the movement of the film which is necessarily effectuated step by step and in general with multiple stops in recording, i.e., at the time of the shooting of the film as well as in the reproduction, i.e., the projection.

Various solutions which have been proposed until now, at least in the field of equipment available to amateurs,'have not given satisfactory results with respect to the flutter phenomena during projection.

SUMMARY OF THE INVENTION The present invention aims at providing a device of the type considered which overcomes this drawback with the use of particularly simple and economical means.

The invention consists essentially of the combination comprising a first driving means having a small inertia which operates intermittently with a second inertia driving means in continuous operation, a recording substrate being continuously coupled to the first driving means and intermittently to the second, said substrate further forming a regulation loop by passing over a swinging regulating roller disposed between the two driving means and adapted to regulate the operating speed of the second driving means tending to reduce the difference between its speed and the speed of the first driving means.

- Experience has shown that owing to this very simple and economical arrangement, it becomes possible to assure in a completely satisfactory manner without any perceptible flutter, the movement of the sound recording substrate concomitantly and on the average synchronously with the frame-by-frame movement of a motion-picture film, the sound recording substrate being an independent magnetic tape operated by a tape recorder or a magnetic track laid on the film per se.

The first driving means preferably comprises a synchronous or stepwise electric motor supplied by a synchronized pulse source which could be either a synchronized pulse generator disposed on the shaft of a camera or of a film projector or the reading head for a track carrying a train of recorded pulses during shooting or projection sequences.

Further features and advantages of the invention will be brought out in the description which follows by way of example with reference to the accompanying drawings.

device according to the invention in the case of its application for the transfer of a sound recording recorded by a tape recorder on the film.

tion-picture film carrying a magnetic sound track. The forward movement of the film in the direction of the arrow 11 is assured by a first driving means comprising a synchronous or a step-wise motor 12 having a very small inertia and supplied by a pilot source 13 through the intermediary of an amplifier 14. In order to effect the movement of the film by the motor, the film 10 is continuously held between the shaft 15 of the motor 12 and a pressure roller 16 continuously in engagement against the shaft. In the present case, either the shaft or the roller can advatangeously include pins or sprockets and the other can include holes corresponding to the perforations in the film.

The movement of the film is further assured by a second inertia driving means comprising a motor 18 whose speed is continuously adjustable and whose shaft carries a pulley 19 coupled by a belt 20 to a fly-wheel 21. The film passes between the shaft 22 of the fly-wheel and the pressure roller 23 disposed at the end of the arm 24 pivoted about a fixed axis 25. The arm 24 is urged by a spring 26 so that the pressure roller is normally positioned away from the shaft 22. This arm is responsive on the other hand to the action of an electromagnet 27 whose armature 28 (shown schematically) is adapted to move it in the direction opposite to that of the force exerted by the spring 26 which assures the contact of the roller 23 against the shaft 22 when the electromagnet 27 is energized.

The film then passes between the two motors along regulating or swinging roller 30 carried by an arm 31 pivotally mounted about the fixed pivot 32 and urged to pivot counter clockwise by the action of a tension spring 33. At its free end the arm 31 carries the sliding contact 34 of a rheostat 35 which is arranged in series in the supply circuit for the motor 18, the motor being supplied by a source 36 which may for example be a DC. current source. The supply circuit 37 is connected to the terminals of the source 36 and controls the energization of the coil of the electromagnet 27, the normally-opened contact 38 of the relay 39 being disposed in this circuit. The energizing windings of this relay are connected by conductors 40 to the output of the amplifier 14 arranged in parallel with the first motor 12 by the intermediary of a rectifier (not shown).

A recording and reproducing head 41 is disposed adjacent to the path of movement of the tape 10 in a position upstream of the second driving means.

The pilot source 13 can comprise a small pulsegenerator coupled to the shaft of a motion-picture camera or a film projector. This source can alternatively comprise, as shown, the reading head for a magnetic track carrying the recording of a train of synchronizing pulses. The signal emitted by the pilot source 13 will therefore in all cases be a train of pulses having a relatively low amplitude (for example 600mV over an impedance of 16K!) or 1.5 V over an impedance of 3 KO).

' motor 12; whereas the electromagnet 27 is sufficiently powerful to assure the application of the pressure roller 23 with sufficient force against the shaft 22 of the flywheel 21. The combination 23-28 therefore constitutes an electromagnetic clutch adapted to assure the movement of the tape on the shaft 22 of the fly-wheel 21 each time the pilot source is activated and effects the movement of the tape by the first motor 12 through the intermediary of the amplifier 14.

In the embodiment of the drawing, the device is used in combination with a tape recorder 42. It is assumed that the film 10 has been developed after the shooting of a series of scenes; and that during this shooting, the tape recorder 42 was used to record on the tape 43 a corresponding series of sound sequences. It is also assumed that on a synchronizing track reserved on the tape 43 is recorded synchronizing signal comprising, as indicated hereinabove, the train of pulses produced by a pulse generator coupled or associated with the shaft of the camera (not shown). The pilot source 13 comprises under these circumstances a reading head cooperating with the synchronizing track of the tape 43, whereas the main reading head 44 of the tape recorder which cooperates with the regular track or tracks of the tape 43 is connected in general through the intermediary of an amplifier (not shown) to the head 41 of the device. This head 41 acts in this case as a recording head whose operation consists of transferring sound sequences recorded on the tape 43 onto a magnetic track of the film 10.

Within the framework of the embodiment of the invention chosen by way of example, the device could be incorporated in a projector in which the first driving means 12, 15, 16 constitute means for effecting forward movement of the film. The projector in this case is brought under the control of the tape recorder 42. When the tape recorder operates and the tape 43 moves, the projector will be started each time that the train of synchronizing pulses appears on the synchronizing track facing the head 13. The pulses amplified at 14 simultaneously assure the starting of the first driving means b energizing the motor 12 and the engagement of the rim against the second driving means whose motor 18 turns continuously at a speed determined by the position of the sliding contact of the rheostat 35. The arrival of the signal at the output of the amplifier 14 simultaneously with the starting of the low-inertia motor 12 effects the energization of the relay 39 which causes the contact 38 to close the circuit 37 which in turn effects the energization of the electromagnet 27 and the movement of the pressure roller 23 against the shaft 22 which acts a driving capstan for the film 10 facing the head 41.

When the tape 43 is stopped, motor 12 also stops since there are no more synchronizing pulses applied to amplifier 14. The film 10 also stops due to permanent engagement of the sprocket holes thereof with sprocket wheel 15 and pinch roller 16. As motor 12 stops, relay 39 is also de-energized, and contact 38 opens, thereby causing the electromagnetic clutch 27, 23 to be deenergized and film 10 to move out of engagement with capstan roller 22. However, motor 18 remains in operation, thus allowing rotation of flywheel 21 and capstan 22 to be maintained substantially at the normal operating speed. In this manner, when motor 12 and clutch 27, 23 are energized again, film 10 is instantaneously restarted up at substantially the correct speed, and transient sound pitch perturbations which would otherwise arise if the high inertia flywheel 31 had to be overcome are thus avoided.

As the movement of the film is effected by jerks, i.e., step by step in the first driving means 12 the movement of the film in front of the magnetic head 41 is assured at a substantially constant speed determined by the rotation of the fly-wheel 21 of the second driving means having a large inertia, and therefore protected from any jerking which could be a source of flutter owing to the fact that the second driving means is in continuous rotation. The speed of rotation will in general be either too great or too small; the loop formed by the film around the roller 30 will tend to elongate or shorten according to the case. In the case of too great a speed of the second driving means, for example the loop will tend to elongate with the displacement of the roller 30 under the force of the spring 33 in the counterclockwise direction; this produces a displacement of the sliding contactdownwards therefore increasing the resistance of the rheostat 35 and thereby slowing down the motor 18. The opposite effect is of course produced in the case of a decrease the speed of the second driving means relative to that of the first. The roller 30 will therefore rise or fall according to the case.

Experience shows that the resulting operation thus regulated is sufficiently stable to render recourse to stabilizing devices which would complicate the construction of the device normally unnecessary. However nothing would prevent the recourse to such devices in certain particular cases without going outside the scope of the invention. This advantageous and desirable stability can be attributed to the combination of a first driving means with small inertia constantly coupled to a second driving means having a large inertia and constantly in rotation and a controlled coupling. More interesting than even this stability of regulation is the substantially constant movement of the film in the region of magnetic head 41. Even in the case of stops which could be frequent between projection sequences, at each restarting thereof, the movement of the film is reestablished instantaneously at a linear speed corresponding to the speed of rotation of the fly-wheel 21. The stopping of the movement of the film is assured in a substantially instantaneous manner under a sole'condition which is easily effected that the delivery reel (not shown) is subjected to a slight braking force. Although, on the other hand, the substantially constant speed of the second driving means is necessarily subjectedto fluctuations resulting from the regulation assured by the movement of the bobbing roller 30; these fluctuations are sufficiently slow and their amplitude remains in practice sufficiently small so as not to affect the quality of the sound in any manner sensible to the ear.

The case which has just been considered with reference to the accompanying drawing is only an example of the various possibilities of using the device according to the invention. In any case, the movement of a film or a magnetic tape is assured by the second driving means at a substantially constant speed proportional to the mean speed of the forward movement of the film in a camera or in a projector in spite of the inevitable fluctuations or stops in this movement. According to another embodiment of the invention, the support 10 may be a magnetic tape, the shaft 15 therefore becomes a capstan drive with an ordinary pressure roller at 16, the synchronizing source 13 is constituted by a pulse generator keyed on the shaft of a camera or a projector; this arrangement enables the control of a tape recorder either by a camera during the shooting of the film or the projector during the projection.

I claim:

1. A strip transport apparatus for advancing along a transport path a strip having a longitudinally disposed sound track synchronously with an external timing reference source, comprising:

first driving means operatively engaging sprocket holes in said strip for intermittently advancing said strip in a first region of thetransport path thereof, said first driving means being fed with externally supplied synchronizing pulses;

second driving means for imparting a substantially continuous translatory movement to the strip in a second region of the transport path thereof;

a magnetic transducer head mounted for cooperating with the sound track of said strip in said second region;

a resiliently biased slack loop forming movable element disposed on the transport path of said strip between said first and second regions;

servocontrol means coupled to said second driving means and responsive to the position of said movable element for continuously equalizing the instantaneous translatory speed of the strip in said second region to the average translatory speed of the strip in said first region;

said second driving means including a motor, a capstan means coupled to said motor and operatively engageable with said strip for imparting thereto said continuous translatory movement, said capstan means having substantially inertia,

and clutch means operable for bringing said capstan means into operative engagement with said strip in response to the energization of said first driving means.

2. A strip transport apparatus according to claim 1, wherein said capstan means includes a capstan roller portion and a flywheel portion coaxially disposed therewith, said fly-wheel portion being coupled to said motor by means of a belt, and wherein said clutch means includes a movable pinch roller mounted for cooperation with said capstan roller portion, an actuator energizable for moving said pinch roller towards said capstan roller portion, and means for energizing said actuator in response to the synchronizing pulses supplied to said first driving means. 

1. A strip transport apparatus for advancing along a transport path a strip having a longitudinally disposed sound track synchronously with an external timing reference source, comprising: first driving means operatively engaging sprocket holes in said strip for intermittently advancing said strip in a first region of the transport path thereof, said first driving means being fed with externally supplied synchronizing pulses; second driving means for imparting a substantially continuous translatory movement to the strip in a second region of the transport path thereof; a magnetic transducer head mounted for cooperating with the sound track of said strip in said second region; a resiliently biased slack loop forming movable element disposed on the transport path of said strip between said first and second regions; servocontrol means coupled to said second driving means and responsive to the position of said movable element for continuously equalizing the instantaneous translatory speed of the strip in said second region to the average translatory speed of the strip in said first region; said second driving means including a motor, a capstan means coupled to said motor and operatively engageable with said strip for imparting thereto said continuous translatory movement, said capstan means having substantially inertia, and clutch means operable for bringing said capstan means into operative engagement with said strip in response to the energization of said first driving means.
 2. A strip transport apparatus according to claim 1, wherein said capstan means includes a capstan roller portion and a flywheel portion coaxially disposed therewith, said fly-wheel portion being coupled to said motor by means of a belt, and wherein said clutch means includes a movable pinch roller mounted for cooperation with said capstan roller portion, an actuator energizable for moving said pinch roller towards said capstan roller portion, and means for energizing said actuator in response to the synchronizing pulses supplied to said first driving means. 